what's behind it? >> well, basically, normally when you get rain, it helps bring more rain. that is the rain eventually evapora evaporates, the moisture of the ground into the air. clouds form. then rain comes down and you get more rain. however, if you've been in a drought condition, the ground gege so dry, there is no moisture to evaporate into the air. clouds don't form and you don't get additional rainfall. so, the doubt can perpetuate. >> a cycle repeating itself across the country. let's talk about relief, harvey. when do we see knee relief and who seeps it first? >> well, the northeastern part of the country, new england and down to new york is going to see it first and it will happy sunday. that's when the jet stream will shift. right now, almost the entire country is stuck with incredible heat and most of it a lot of humidity. but as the jet stream shifts south across the northeast, c cl air will come down from canada. the problem is, the middle of the country, the plains, the southern states, i don't see a break coming any time soon. >> no relief for them, possibly weeks.